Throughout his life, Hevelius took a leading part in
municipal administration, becoming
town councillor in 1651; but from 1639 on, his chief interest was
astronomy. In 1641 he built an
observatory on the roofs of his three connected houses, equipping it with splendid instruments, ultimately including a large
Keplerian telescope of
focal length, s on his rooftop observatorium. The observatory was known by the name
Sternenburg (; ) or "Star Castle". Polish Queen
Marie Louise Gonzaga visited this private observatory on 29 January 1660. As a subject of the Polish kings, Hevelius enjoyed the patronage of four consecutive kings of Poland, and his family was raised to the position of nobility by the King of Poland
John II Casimir in 1660, who previously visited his observatory in 1659. While the noble status was not ratified by the Polish
Sejm Hevelius's coat of arms includes the distinctive Polish royal crown. The
Polish King John III Sobieski who regularly visited Hevelius numerous times in years 1677–1683 released him from paying taxes connected to brewing and allowed his beer to be sold freely outside the city limits. In May 1679 the young Englishman
Edmond Halley visited him as emissary of the
Royal Society, whose fellow Hevelius had been since 1664. The Royal Society considers him one of the first German fellows. Małgorzata Czerniakowska (2005) writes that "Jan Heweliusz was the first Pole to be inducted into the Royal Society in London. This important event took place on 19th March 1664". Hevelius considered himself as being citizen of the Polish world (
civis Orbis Poloniae) and stated in a letter dated from 9 January 1681 that he was
Civis orbis Poloni, qui in honorem patriae suae rei Literariae bono tot labores molestiasque, absit gloria, cum maximo facultatum suarum dispendio perduravit, i.e. "citizen of Polish world who, for glory of his country and for the good of science, worked so much, and while not boasting much, executed his work with most effort per his abilities". Halley had been instructed by
Robert Hooke and
John Flamsteed to persuade Hevelius to use
telescopes for his measurements, yet Hevelius demonstrated that he could do well with only
quadrant and
alidade. He is thus considered the last astronomer to do major work without the use of a telescope. Hevelius made observations of
sunspots, 1642–1645, devoted four years to charting the lunar surface, discovered the
Moon's
libration in longitude, and published his results in
Selenographia, sive Lunae descriptio (1647), a work which entitles him to be called "the founder of lunar
topography". ==Works==